What happens to the uterus between each ovulation?

The uterus goes through several changes during the menstrual cycle, which is typically around 28 days. Between each ovulation, which occurs around day 14 of the cycle, the uterus undergoes the following phases:

1. Proliferative Phase:

- After menstruation, the uterus starts to prepare for a potential pregnancy.

- The levels of the hormone estrogen rise, which stimulates the growth and thickening of the endometrium (the lining of the uterus).

- Estrogen promotes the proliferation of endometrial cells, blood vessels, and glands.

- The endometrium becomes thicker and more receptive to a fertilized egg.

2. Ovulation:

- Around day 14 of the cycle, ovulation occurs when a mature egg is released from one of the ovaries.

- This process is triggered by a surge in luteinizing hormone (LH) from the pituitary gland.

3. Secretory Phase:

- After ovulation, the corpus luteum (a structure formed from the ruptured ovarian follicle) produces progesterone.

- Progesterone further stimulates the growth and development of the endometrium.

- The blood vessels in the endometrium become more prominent and the glands start to secrete nutrients to support a potential embryo.

- The endometrium becomes fully prepared to receive and nourish a fertilized egg.

4. Menstruation:

- If fertilization and implantation of a fertilized egg do not occur, the corpus luteum begins to regress, leading to a decrease in progesterone and estrogen levels.

- The endometrium is no longer supported and starts to break down and shed.

- This shedding of the endometrium along with blood and mucus results in menstruation or a period.

- The menstrual flow lasts for approximately 3-7 days.

5. Transition:

- After menstruation, the uterus starts to repair and prepare for the next cycle.

- The remaining endometrial lining is shed and the hormone levels return to their basal levels.

- The uterus is at its smallest size during this phase.

6. Quiescent Phase:

- This phase occurs just before ovulation and is a brief period of relative inactivity in the uterus.

- The endometrium is thin and the uterus is preparing to receive a fertilized egg.

The uterus undergoes these cyclical changes each month in preparation for a possible pregnancy. If pregnancy occurs, the endometrium continues to thicken and develop to support the growing embryo and fetus. If pregnancy does not occur, the endometrium is shed during menstruation and the cycle starts again.